Maybe run a couple of cans of diesel purge through the system - if anything it will run smoother.

Check the air flow -> filter condition, check for blockage in the u-bend going from the air assembly to the turbo. I remember someone leaving a rag in there once.... doh! With the u-bend off, does the turbo spin freely?

I found the biggest performance kick from doing a valve adjustment on my 83SD (184K mi)- like night and day off the line. Almost all the clearances were too tight (engine was not breathing well). If you have the tools and the knowledge - it's almost a zero cost thing to do ($ new gasket). If you have the service records it is something to check if it has been done. It is recommended 15K miles, but you can go longer.

__________________
~shell
As of 2/2010:
2001 CLK55 0o\=*=/o0
13.6 @ 106mph
10K mi
1984 300SD
260K mi and going and going...
97 S600
46K miles
1991 Sentra SE-R (extremely dorked with)
www.se-r.net